An accurate<i>ab initio</i>study of the multipole moments and polarizabilities of methane

Abstract

Accurate calculations are made using SCF and CI wavefunctions of the properties of methane. The properties considered are the octopole and hexa-decapole moments, the polarizability, hyperpolarizability and dipole-quadrupole polarizability, the diamagnetic contributions to the nuclear magnetic shielding constants, and to the magnetizability, and the electric field gradient at the hydrogen nucleus. Where accurate experimental values are known these are found to be in excellent agreement with the ab initio values. The accuracy of determining multipole moments and polarizabilities from collision induced spectra is discussed.